Process for the preparation of enantiomerically pure cycloalkano-indol -and azaindol -and pyrimido [1,2A]indolcarbocyclic acids and their activated derivatives

ABSTRACT

The invention relates to a process and intermediates for the preparation of enantiomerically pure cycloalkanoindolecarboxylic acids and azaindolecarboxylic acids and pyrimido[1,2a]indolecarboxylic acids and their activated derivatives, characterized in that the tolyl acetic acid is first esterified with a chiral alcohol, then diastereoselective substitution at α-carbon atoms is carried out and this product is halogenated in the tolyl group and then reacted with appropriate cycloalkanoindoles, cycloalkanoazaindoles or pyrimido[1,2a]indoles. It is possible by this method to prepare specifically, in high purity, the enantiomerically pure carboxylic acids which are intermediates for valuable medicaments.

This application is a division of Ser. No. 08/829,566 filed on Mar. 31,1997, now Pat. No. 5,952,498, which claims priority to GermanApplication 196 13 549.4 filed on Apr. 4, 1996.

The invention relates to a process for the preparation ofenantiomerically pure cycloalkano-indolecarboxylic acids andazaindolecarboxylic acids and pyrimido[1,2a]indolecarboxylic acids andtheir activated derivatives, which represent important intermediates forthe synthesis of antiatherosclerotically active cycloalkanoindolederivatives and azaindole derivatives and pyrimido[1,2a]indolederivatives.

It is known that enantiomerically pure cycloalkano-indolecarboxylicacids and azaindole-carboxylic acids and their activated derivatives canbe separated into the corresponding enantiomers by diastereomericseparation by conventional methods, for example by chromatography orfractional crystallization.

This process has a number of disadvantages: both the chromatographicdiastereomeric separation and the fractional crystallization of thediastereomers are associated with high equipment requirements. Inaddition, in this case, generally 50% of the “wrong” diastereomerarises, which can no longer be recycled to the original preparationprocess.

This 50% loss of yield considerably impairs the economic efficiency of a(large) industrial-scale process, quite apart from the fact that 50% of“by-product” must be disposed of. Furthermore, the customary chiralauxiliary reagents are generally very expensive even in small amountsand can then usually only be prepared via a complex synthetic pathway.

It has now been found that enantiomerically purecycloalkano-indolecarboxylic acids and azaindolecarboxylic acids andpyrimido[1,2a]indole-carboxylic acids and their activated derivates ofthe general formula (I)

in which

A represents a radical of the formula

 or

J, D, E, G, L and M are identical or different and denote hydrogen,halogen, trifluoromethyl, carboxyl, hydroxyl, linear or branched alkoxyor alkoxycarbonyl each having up to 6 carbon atoms, or linear orbranched alkyl having up to 6 carbon atoms, which itself can besubstituted by hydroxyl or by linear or branched alkoxy having up to 4carbon atoms,

in which

R¹ and R², including the double bond linking them, together form aphenyl ring or pyridyl ring or a ring of the formula

 where

R⁵ denotes hydrogen or linear or branched alkyl having up to 4 carbonatoms,

R³ and R⁴, including the double bond linking them, together form aphenyl ring or a 4- to 8-membered cycloalkene or oxocycloalkene radical,where all the ring systems listed under R¹/R² and R³/R⁴ are optionallyup to trisubstituted identically or differently by halogen,trifluoromethyl, carboxyl, hydroxyl, by linear or branched alkoxy oralkoxycarbonyl each having up to 6 carbon atoms, or by linear orbranched alkyl having up to 6 carbon atoms, which itself can besubstituted by hydroxyl or by linear or branched alkoxy having up to 4carbon atoms,

T represents cycloalkyl having 4 to 12 carbon atoms, or representslinear or branched alkyl having up to 12 carbon atoms,

Q represents hydroxyl or an activating radical,

and their salts are obtained

by firstly converting compounds of the general formula (II),

in which

R⁶ together with the oxygen atom represents a chiral alcohol radical, bymeans of compounds of the general formula (III)

T—Z  (III)

 in which

T has the meaning specified and

Z represents a typical leaving group, such as bromine, chlorine, iodine,mesyl, tosyl, or trifluoromethylsulphonyl, preferably iodine or bromine,

n inert solvents in the presence of a base by diastereoselectivealkylation into the enantiomerically pure compounds of the generalformula (IV)

in which

T and R⁶ have the meaning specified,

then converting these, by halogenation, into the enantiomerically purecompounds of the general formula (V)

in which

T and R⁶ have the meaning specified

and

R⁷ represents halogen, such as chlorine, bromine, iodine, preferablybromine, reacting these in a further step with compounds of the generalformula (VI)

A—H  (VI)

in which

R¹, R², R³ and R⁴ have the meaning specified,

to give the enantiomerically pure compounds of the general formula (VII)

in which

A, T and R⁶ have the meaning specified,

and, in the case of compounds of the general formula (I) where Q═OH,carrying out a hydrolysis, and in the case where Q=activating radical,starting from the enantiomerically pure acids reacting with activatingreagents.

These can be reacted in a further step with D- or L-phenylglycinol togive compounds of the general formula (VIII)

where these are in this case active compounds for medicaments.

The process according to the invention can be described by way ofexample by the following formula diagram:

Surprisingly, the process according to the invention gives the wantedenantiomerically pure cycloalkano-indolecarboxylic acids andazaindole-carboxylic acids and pyrimido-indolecarboxylic acids and theiractivated derivatives without great equipment requirements in very goodyields and high purity.

Depending on the configuration of the radical R⁶ and stearic effects ofthe alkyl halide (II) used, the alkylation of the compound (II) proceedsin high yields and in a simple manner diastereoselectively for the firsttime. The compounds (IV) arise with high diastereomeric excess andcrystallize out of the reaction mixture directly, as a result of whicheven the simple crystallization of crude products gives the compounds ofthe formula (IV) in diastereomerically pure form.

A further advantage of the process according to the invention is that,by suitable choice of the solvent and a base, the unwanted diastereomercan be epimerized to the desired diastereomer, which in turncrystallizes out directly. Thus, further (wanted) diastereomericallypure product can be produced from the mother liquors by repeatedepimerization and crystallization. Direct addition of the mother liquorsto the alkylation step can optimize the entire process in the form of acyclic process.

A further advantage of the process according to the invention is thatthe halogenated compounds of the general formula (V) surprisingly reactwith the compounds of the general formula (VI) without racemization atthe carbon atom in the 2 position to the carboxylic acid function, togive the compounds of the general formula (VII).

A further advantage of the process according to the invention is theracemization-free reaction at the carbon atom at the 2 position to thecarboxylic acid function of the compounds of the general formula (I)where Q=activated radical, preferably chlorine, to give the compounds ofthe general formula (VIII).

Furthermore, it is a great advantage of the process according to theinvention that the starting compounds are very readily accessible. Theymay be prepared in good yields from relatively simple building blockswith low equipment requirements. Furthermore, the process according tothe invention enables amounts of known racemates of the compounds of thegeneral formula (I) present to be converted into the correspondingenantiomers. The process according to the invention enables thepreparation of the compounds according to the invention of the generalformula (I) using few synthetic stages and in a considerably higheroverall yield than by processes known from the prior art.

R⁶, in the context of the above specified definition, represents achiral alcohol radical, such as (+)- or (−)-menthyl, (+)- or (−)-bornyl,(+)- or (−)-isobornyl or (−)-8-phenylmenthyl. Preferably, R⁹ represents(+)- or (−)-menthyl.

Activating radicals (Q), in the context of the invention, generallyrepresent chloride, bromide, mesylate, tosylate or trifluoride.Preference is given to chloride. Preferably, by the process according tothe invention, compounds of the general formula (I) are prepared, inwhich

A represents a radical of the formula

in which

J, D, E, G, L and M are identical or different and denote hydrogen,fluorine, chlorine, bromine trifluoromethyl, carboxyl, hydroxyl, linearor branched alkoxy or alkoxycarbonyl each having up to 4 carbon atoms,or linear or branched alkyl having up to 4 carbon atoms which itself canbe substituted by hydroxyl or by linear or branched alkoxy having up to3 carbon atoms, R¹ and R², including the double bond linking them,together form a phenyl ring or pyridyl ring or a ring of the formula

 in which

R⁵ denotes hydrogen or linear or branched alkyl having up to 3 carbonatoms,

R³ and R⁴, including the double bond linking them, together form aphenyl ring or a cyclopentene, cyclohexene, cycloheptene, cyclooctene,oxocyclopentene, oxocyclohexene, oxocycloheptene or oxocycloocteneradical,

 where all ring systems, listed under R¹/R² and R³/R⁴ are optionally upto disubstituted identically or differently by fluorine, chlorine,bromine, trifluoromethyl, carboxyl, hydroxyl, by linear or branchedalkoxy or alkoxycarbonyl each having up to 4 carbon atoms, or by linearor branched alkyl having up to 4 carbon atoms, which itself can besubstituted by hydroxyl or by linear or branched alkoxy having up to 3carbon atoms,

T represents cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl,cyclooctyl, or represents linear or branched alkyl having up to 10carbon atoms,

Q represents hydroxyl or represents an activating radical,

and their salts.

Particularly preferably, compounds of the general formula (I) areprepared by the process according to the invention in which

A represents a radical of the formula

in which

J, D, E, G, L and M are identical or different and denote hydrogen,fluorine, chlorine, bromine, trifluoromethyl, carboxyl, hydroxyl, linearor branched alkoxy or alkoxycarbonyl each having up to 3 carbon atoms,or denote linear or branched alkyl having up to 3 carbon atoms,

R¹ and R², including the double bond linking them, together form aphenyl ring or pyridyl ring or a ring of the formula

 in which

R⁵ denotes hydrogen or methyl,

R³ and R⁴, including the double bond linking them, together form aphenyl ring or a cyclopentene, cyclohexene, cycloheptene, cyclooctene,oxocyclopentene, oxocyclohexene, oxocycloheptene or oxocycloocteneradical,

where all ring systems listed under R¹/R² and R³/R⁴ are optionally up todisubstituted identically or differently by fluorine, chlorine, bromine,trifluoromethyl, carboxyl, hydroxyl, by linear or branched alkoxy oralkoxycarbonyl each having up to 3 carbon atoms or by linear or branchedalkyl having up to 4 carbon atoms which itself can by substituted byhydroxyl, methoxy or ethoxy.

T represents cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl or linearor branched alkyl having up to 6 carbon atoms,

Q represents hydroxyl or an activating radical,

and their salts.

Very particularly preferably, the compounds of the general formula (I),in which

A represents a radical of the formula

 in which

R³ and R⁴=phenyl ring

and having the radical *CH—T—COQ in the paraposition and Q=chlorine, andtheir salts,

are prepared by the above described process.

Suitable solvents for the alkylation of the compound of the generalformula (II) are customary organic solvents which do not change underthe reaction conditions. These preferably include ethers, such asdiethyl ether, diisopropyl ether, tert-butyl methyl ether, dioxane,tetrahydrofuran, glycol dimethyl ether, or hydrocarbons, such asbenzene, toluene, xylene, hexane, cyclohexane or mineral oil fractions,or halogenated hydrocarbons, such as dichloromethane, trichloro-methane,tetrachloromethane, dichloroethylene, trichloroethylene orchlorobenzene, or ethyl acetate, triethylamine, pyridine, dimethylsulphoxide, dimethylformamide, N-methylpyrrolidone, hexamethylphosphorictriamide, acetonitrile, acetone or nitromethane, methanol or ethanol. Itis equally possible to use mixtures of the said solvents. Preference isgiven to dimethylformamide.

The alkylation is carried out in the solvents listed above, ifappropriate under a protective gas atmosphere, at temperatures of −20°C. to +100° C., preferably at −10° C. to +30° C., at atmosphericpressure.

Suitable bases for the diastereoselective alkylation are the customarybasic compounds. These include alkali metal hydrides, such as sodiumhydride, alkyli metal amides such as sodium amide, alkali metalalkoxides, such as sodium methoxide, sodium ethoxide, potassiummethoxide, potassium ethoxide or potassium tert-butoxide, or organicamines, such as trialkylamines, e.g. triethylamine, or organolithiumcompounds, such as butyllithium or phenyllithium. Preference is given topotassium tert-butoxide.

In the diastereoselective alkylation, the base is used in an amount from1 mol to 10 mol, preferably from 1.2 mol to 3 mol, based on 1 mol of thecompounds of the general formula (II).

Suitable solvents for the halogenation of the compound for the generalformula (IV) are customary solvents which do not change under thereaction conditions. These preferably include tetrachloromethane,chlorobenzene, dichlorobenzene, acetonitrile, acetic acid, sulphuricacid, nitrobenzene, 1,2-dichloroethane, dichloromethane,trichloromethane.

For the halogenation, customary halogenating agents are suitable, suchas bromine, chlorine, NBS, NCS, dichlorodimethylhydantoin,dibromodimethylhydantoin, trichlorisocyanuric acid, chloramine-T.

Suitable free-radical starters are, for example, AIBN, peroxides, suchas dibenzoyl peroxide, t-butyl hydroperoxide, dilauryl peroxide, t-butylperoxide, butyl perbenzoate, di-t-butyl peroxalate, and photochemicalmethods.

The halogenation is carried out in the solvents listed above, ifappropriate under a protective gas atmosphere, at temperatures of 20° C.to 180° C., if appropriate under pressure. Preferably, the halogenationis carried out at 70° C. to 130° C.

In the halogenation, the halogenating agent is used at 0.8 mol to 1.7mol of active halogen, based on 1 mol of the compounds of the generalformula (I).

Suitable solvents for the alkylation of the compound of the generalformula (VI) are customary organic solvents which do not change underthe reaction conditions. These preferably include ethers, such asdiethyl ether, diisopropyl ether, tert-butyl methyl ether, dioxane,tetrahydrofuran, glycol dimethyl ether, or hydrocarbons, such asbenzene, toluene, xylene, hexane, cyclohexane or mineral oil fractions,or halogenated hydrocarbons, such as dichloromethane, trichloromethane,tetrachloromethane, dichloroethylene, trichloroethylene orchlorobenzene, or ethyl acetate, triethylamine, pyridine, dimethylsulphoxide, dimethylformamide, N-methylpyrrolidone,hexamethyl-phosphoric triamide, acetonitrile, acetone or nitromethane.It is equally possible to use mixtures of the said solvents. Preferenceis given to dimethylformamide, toluene and tetrahydrofuran.

The alkylation is carried out in the solvents listed above, ifappropriate under a protective gas atmosphere, at temperatures of −20°C. to +100° C., preferably at −10° C. to +30° C., at atmosphericpressure.

Suitable bases are generally inorganic or organic bases. Thesepreferably include alkali metal hydroxides, such as sodium hydroxide orpotassium hydroxide, alkaline earth metal hydroxides, such as bariumhydroxide, alkali metal carbonates and alkali metal hydrogen carbonates,such as sodium carbonate, sodium hydrogen carbonate or potassiumcarbonate, alkaline earth metal carbonates, such as calcium carbonate,or alkali metal alkoxides or alkaline earth metal alkoxides, such assodium methoxide or potassium methoxide, sodium ethoxide or potassiumethoxide or potassium tert-butoxide, or organic amines (trialkyl(C₁-C₆)amines), such as triethylamine, or heterocylcles, such as1,4-diazabicyclo[2,2,2]octane (DABCO),1,8-diazabicyclo[5,4,0]undec-7-ene (DBU), pyridine, diaminopyridine,methylpiperdine or morpholine. It is also possible to use alkali metals,such as sodium, or their hydrides, such as sodium hydride, as bases.Preference is given to sodium hydrogen carbonate, potassium carbonateand potassium tert-butoxide, DBU or DABCO.

In the alkylation, the base is used in an amount of 1 mol to 10 mol,preferably of 1.2 mol to 3 mol, based on 1 mol of the compounds of thegeneral formula (II).

To eliminate the chiral radical R⁶ in the compounds of the generalformula (VII), the customary organic carboxylic acids are suitable, suchas acetic acid, formic acid, trifluoroacetic acid, methanesulphonicacid, or inorganic acids, such as hydrobromic acid, hydrochloric acid orsulphuric acid or mixtures of the said acids. Preference is given toacetic acid, formic acid, hydrobromic acid and/or sulphuric acid. Veryparticular preference is given to the mixture acetic acid/sulphuric acidand also formic acid/hydrobromic acid and formic acid/sulphuric acid.

The acids or their mixtures are simultaneously employed as solvent andthus used in a great excess.

The elimination proceeds in a temperature range from 0° C. to +150° C.,preferably from 40° C. to 100° C.

It can generally be carried out at atmospheric pressure, but optionallyalternatively at superatmospheric pressure or reduced pressure (e.g. 0.5to 3 bar).

After neutralization with bases in water or in one of the solventslisted above, in particular in a water/toluene, water/isopropanol,water/methanol or water/ethanol mixture, the acids are worked up by acustomary method.

Suitable bases for the neutralization are alkali metal hydroxides, suchas sodium hydroxide or potassium hydroxide. Preference is given tosodium hydroxide.

Suitable solvents for the activation of the compounds of the generalformula (I) are customary organic solvents which do not change under thereaction conditions. These preferably include ethers, such as diethylether, diisopropyl ether, tert-butyl methyl ether, dioxane,tetrahydrofuran, glycol dimethyl ether, or hydrocarbons, such asbenzene, toluene, xylene, hexane, cyclohexane or mineral oil fractions,or halogenated hydrocarbons, such as dichloromethane, trichloromethane,tetrachloromethane, dichloroethylene, trichloroethylene orchlorobenzene, or ethyl acetate, triethylamine, pyridine, dimethylsulphoxide, dimethylformamide, acetonitrile, acetone or nitromethane. Itis equally possible to use mixtures of the said solvents. Preference isgiven to dimethylformamide, toluene and dichloromethane.

For the activation, conventional activation agents are suitable, forexample oxalyl chloride, phosphorus trichloride, phosphoruspentachloride, trichloroisocyanuric acid, thionyl chloride, phosphorustribromide, phosphorus pentabromide, mesyl chloride, tosyl chloride,phosgene, trifluoromethanesulphonyl chloride, sulphuryl chloride.Preference is given to thionyl chloride, oxalyl chloride and phosgene.

The activation is carried out in the solvents listed above, ifappropriate under a protective gas atmosphere, at temperatures of −20°C. to 120° C., optionally under pressure. Preferably, the activation iscarried out at −20° C. to 80°.

In the activation, the activation reagent is used in an amount of 1 molto 10 mol, based on 1 mol of the compound of the general formula (I), oris optionally employed as solvent.

The activation is optionally performed with the addition of bases, suchas organic amines (trialkyl(C₁-C₆)amines), such as triethylamine, orheterocycles, such as 1,4-diazabicyclo[2,2,2]octane (DABCO),1,8-diazabicyclo[5,4,0]undec-7-ene (DBU), pyridine, diaminopyridine,methylpiperidine or morpholine. If appropriate, the activatedderivatives can be prepared starting from carboxylic salts of alkalimetals and alkaline earth metals by reaction with, e.g., oxalylchloride.

The compounds of the general formula (II),

in which

R⁶ represents a chiral alcohol radical,

are obtained

by esterifying compounds of the general formula (IX)

with chiral alcohols according to processes disclosed in the literature.

The compounds of the general formula (IX) are known per se or can beprepared by customary methods.

The enantiomerically pure compounds of the general formula (I) in whichQ represents tert-butoxy are novel and can be prepared by firstconverting racemic carboxylic acids of the general formula (X)

in which

T has the meaning specified above, by reaction with (R)- or(S)-phenylethylamine in inert solvents and subsequent crystallization ofthe phenethylammonium salts and subsequent hydrolysis of the salts, intothe enantiomerically pure compounds of the general formula (XI)

in which

T has the meaning specified above,

converting these in a further step with isobutene, in inert solvents andin the presence of acids, into the enantiomerically pure esters (XII)

in which

T has the meaning specified above,

then converting the esters (XII) by halogenation into theenantiomerically pure compounds of the general formula (XIII)

in which

T has the meaning specified above

and

R⁷ represents a typical leaving group, such as chlorine, bromine,iodine, tosylate or mesylate, preferably bromine,

in a further step, by reaction with compounds of the general formula(VI)

A—H  (VI)

in which

A has the meaning specified above,

preparing the enantiomerically pure compounds of the general formula (I)

in which

A and T have the meaning specified above and

Q represents tert-butyl,

and in the case of the compounds of the general formula (I) where Q═OH,carrying out a hydrolysis.

Tert-butyl esters are generally saponified with acids, for examplehydrochloric acid or trifluoroacetic acid, in the presence of one of theabove specified solvents and/or water or their mixtures, preferably withdioxane or tetrahydrofuran.

The compounds of the general formula (X) are prepared from thecorresponding esters disclosed in the literature by hydrolysis accordingto methods disclosed in the literature.

EXAMPLE I

2.0 kg (7.2 mol) of tert-butyl2(R,S)-2-cyclopentyl-2-(4-methylphenyl)-acetate are dissolved in 4 l ofdioxane in a 40 l agitated vessel fitted with an attached washing tower.After addition of 4.5 l of concentrated hydrochloric acid, the mixtureis stirred at 50° C. to complete conversion (3 h). The reaction mixtureis admixed with ice and adjusted to pH=12 with concentrated sodiumhydroxide solution. After addition of water to complete solution of thesolids, the mixture is washed with acetic acid, the organic phase iswashed with dilute sodium hydroxide solution and the combined aqueousphases are adjusted to pH=1, with cooling, with concentratedhydrochloric acid. The mixture is washed twice with ethyl acetate, driedover sodium sulphate and concentrated.

Yield: 1.27 kg; 81% of theory. Melting point: 92° C. R_(f)=0.20(petroleum ether:ethylacetate=4:1) ¹H-NMR (CDCl₃, 200 MHz, TMS): δ=0.98(m, 1H); 1.20-1.71 (m, 6H); 1.82-2.05 (m, 1H); 2.31 (s, 3H); 2.52 (m,1H); 3.21 (d, 1H); 7.10 (m, 2H); 7.21 (m, 2H); 11.90 (br, s, 1H) ppm.

EXAMPLE II

2.4 1 of THF and 129.7 g (1.28 mol) of triethylamine are added, withstirring, to a suspension of 560 g (2.57 mol) of the compound fromExample I in 4.8 l of water. The resulting solution is heated to 60° C.,155.4 g (1.28 mmol) of (S)-(−)-phenethylamine are added and theresulting suspension is stirred for 2 h at 60° C. The reaction mixtureis cooled to 20° C., the precipitate is filtered off by suction, washedwith 2.4 l of water/FHF (2:1) and dried under reduced pressure.

Yield: 360 g of phenethylammonium salt; 41.3% of theory. 745 g (2.2 mol)of phenethylammonium salt are suspended in 3 l of water, acidified(pH=1) with dilute hydrochloric acid (1:1) and stirred for 30 minutes.The oily suspension is washed 3 times, each time with 1 l ofdichloromethane, the combined organic phases are now washed with water,dried over sodium sulphate and concentrated, the residue crystallizingout.

Yield: 475 g; 37.3% of theory, based on racemate of Example No. I ee:96.3% (HPLC) Melting point: 66° C.

By crystallization of the phenethylammonium salt from THF, as describedabove, the pure enantiomer is obtained:

ee: >99.5% (HPLC) Specific rotation: [α]_(D) ²⁰=+59.55 (ethanol/c=0.85)

The HPLC method for determination of the ee value is as follows:

Column: Chiracel OJ (Daicel) Particle size: 10μ Packing: 250 × 2 mm(Grom) Mobile phase: n-heptane: 2-propanol = 97:3 Flow rate: 0.2 ml/minInlet pressure: 22 bar

EXAMPLE III

6 ml of concentrated sulphuric acid are added to a solution of 465 g(2.13 mol) of the compound from Example II in 1.4 l of dichloromethane,a temperature of approximately 10° C. being established. 550 ml (5 mol)of isobutene are condensed in a Dewar flask and added in one portion tothe starting material solution. The reaction mixture is stirred overnight. To complete the reaction, a further 6 ml of concentratedsulphuric acid and 500 ml of isobutene are added and stirred over night.After addition of 40 g of potassium carbonate, the mixture is stirredfor 3 h. and then 2 l of water are added, vigorous gas developmentinitially occurring. The mixture is washed three times, each time with 2l of dichloromethane, the combined organic phases are washed with 5 l ofsodium chloride solution, dried over sodium sulphate and concentrated togive an oil which slowly crystallizes.

Yield: 480 g; 82% of theory Melting point: 45° C. R_(f)=0.90(toluene:ethyl acetate=8:2)

EXAMPLE IV

In a 10 l flask, 480 g (1.75 mol) of the compound from Example III aredissolved under reflux in 3.4 l of tetrachloromethane and 70 g of atotal amount of 311 g (1.75 mol) of NBS and 14 g (0.085 mol) of AIBN areadded. The reaction begins after refluxing for approximately 1 h; afterit decays, further NBS is added in 50 g portions. After refluxing for 5h and subsequent standing over night at room temperature, for thework-up, the mixture is cooled to 0° C., the succinimide is filtered offwith suction and washed with 600 ml of tetrachloromethane. The combinedfiltrates are concentrated and residual solvent is removed under reducedpressure to constant weight.

Crude yield: 570 g; approximately 100% of theory HPLC: 68.8% (15.5%starting material, 10.1% dibromo compound) The pure substance isobtained by column chromatography

R_(f)=0.42 (petroleum ether, ethyl acetate=20/1) ¹H-NMR (CDCl₃, 200 MHz,TMS): δ=0.98 (m, 1H); 1.22-1.71 (m, 6H); 1.40 (s, 9H); 1.90 (m, 1H);2.47 (m, 1H); 3.16 (d, 1H); 4.49 (s, 2H); 7.32 (m, 4H) ppm.

EXAMPLE V

3.15 kg of p-tolylacetic acid and 9.45 l of toluene are introduced.3.115 kg of L-menthol and 21.4 ml of methanesulphonic acid are addedwith stirring and cooling. The mixture is then heated to refluxtemperature and the corresponding amount of water is separated off inthe course of 16 to 20 hours via a water separator. After cooling toroom temperature, the mixture is stirred once with 4.41 l of saturatedsodium hydrogen carbonate solution and twice, each time with 4.41 l ofwater. The organic phase is freed from solvent and gives 5.725 kg of thewanted compound (GC 99.9%, retention time 19.49 min). ¹H-NMR (CDCl₃,ppm): 7.05-7.15 (4H, m); 4.55 (1H, txd); 3.5 (2H, s); 2.8 (3H, s); 0.65(3H, s).

EXAMPLE VI

1.575 kg of potassium tert-butoxide are dissolved in 3.75 l of DMF atroom temperature. The mixture is cooled to 10° C. and, in the course of45 minutes, 2.678 kg of the compound from Example V are run in at thistemperature and rinsed with 0.375 l of DMF. Then, with full cooling,1.658 kg of cyclopentyl bromide are pumped in in the course of 1 to 2hours. The suspension is further stirred for 1 hour without cooling andthen cooled to −7° C. When −10° C. is reached, the mixture is seededwith the correct diastereomer and then further cooled to −7° C. When −7°C. is reached, the mixture is further stirred for 3 to 4 hours at thistemperature. The reaction suspension is worked up by introducing it intoa mixture of 1.5 kg of ice and 6 kg of water. The batch is then stirredover night at 0 to 2° C. It is worked up by filtering off the suspensionwith suction and washing the crystals with a total of 2.5 of water. Thecrystals are dried at 45° C. in a vacuum drying cabinet. 3.289 kg of an85 to 15 diastereomer mixture are obtained.

4.345 kg of a mixture prepared as described above are dissolved in 21.751 at 30 to 35° C. After seeding with the correct diastereomer andcooling to room temperature, the mixture is stirred over night andcooled the next morning to 0 to 5° C. After 1 to 2 hours at thistemperature, the crystals are filtered off with suction, dried orrecrystallized. By repeating the methanol crystallization once or twice,material having a diastereomeric purity ≧99.5% can be prepared (GCretention time 22.61 min).

The yield of diastereomerically pure title compound is 65-70% over thestages cyclopentylation and pure crystallization and can be increased to75-80% by recrystallization and by epimerization of the mother liquorswith potassium tert-butoxide in DMF and recrystallization of the crudediastereomer mixture. ¹³C-NMR (CDCl₃, CH-signal, ppm): 128.90; 128.92;73.96; 57.85; 46.92; 42.13; 31.28; 25.96.

EXAMPLE VII

1.40 kg of the compound from Example VI are heated to 80° C. in 13.74 lof chlorobenzene. 0.618 kg of 1,3-dibromo-5,5-dimethylhydantoin are thenadded and the mixture is further heated to 85° C. 20.4 g of AIBN arethen added at this temperature to start the reaction. The temperatureincreases after the start of the reaction to 90 to 105° C., but thendecreases again to about 85° C. The mixture is allowed to react furtherfor a total of 2 hours. The vessel contents are then cooled to roomtemperature and further stirred for one hour. The precipitated crystalsare filtered off with suction and the filtrate is freed from solvent.The remaining oil is 61.2% pure according to HPLC analysis (retentiontime: 14.68 min). 1.69 kg are obtained. The mixture can be used in thecrude state in the following alkylations. Chromatography and subsequentcrystallization give a white powder at melting point 57-58° C. havingthe correct CH analysis.

¹H-NMR (CDCl₃, ppm): 7.3 (4H, s); 4.65 (1H, txd); 4.45 (2H, s); 3.35(1H, d); 0.65 (3H, d).

EXAMPLE VIII

The reaction is carried out under a nitrogen atmosphere. 480 g (2.44mol) of carboline are suspended in 4.13 l of dimethylformamide and 287.7g of potassium tert-butoxide dissolved in 1 l dimethylformamide areadded, with stirring. The reaction solution heats to 30° C. After 30min, the batch is cooled to 20° C. 1.707 kg (2.69 mol) of 69% strengthmenthyl ester bromide, dissolved in 1.56 l of dimethylformamide, arethen added dropwise in such a manner that the internal temperature doesnot exceed 35° C. After a further 15 min of reaction time, the reactionsolution is poured into a mixture of 1.8 l of 10% strength sodiumchloride solution and 13 l of ethyl acetate. After 20 min, withstirring, the ethyl acetate phase is separated off and extracted twice,each time with 3 of 10% strength sodium chloride solution. After dryingthe organic phase over sodium sulphate, ethyl acetate is distilled offunder reduced pressure at approximately 40° C. The syrupy residue istaken up in 4.4 l of methanol and stirred for 30 min under reflux atroom temperature for 12 h. The precipitated crystals are filtered offwith suction, washed with methanol and dried under reduced pressure at40° C.

Yield: 947 g(70.6% of theory) Melting point: 142° C.

EXAMPLE IX

947 g (1.72 mol) of the compound from Example VIII are admixed with 2.4l of formic acid. 1.21 l of aqueous hydrobromic acid (48% strength) areadded dropwise with stirring. The resulting suspension is stirred for 6hours at 95-98° C. and then cooled to room temperature. The reactionsolution is admixed with 1.6 l of isopropanol and 3.2 l of water, withstirring. A pH of 5 is established with 45% strength sodium hydroxidesolution, with gentle cooling (consumption of sodium hydroxide solution:5.2 kg). The precipitate is filtered off with suction, washed twice with5.7 l of water and sucked dry. The water-moist product is then stirredin 2.6 l of isopropanol for 2 hours at room temperature. The crystalsare filtered off with suction, washed with 2.8 l of isopropanol anddried under reduced pressure at 60° C.

Yield: 574 g (81% of theory) Melting point: 197-199° C.

EXAMPLE X

A suspension of 350 g (0.85 mol) of the compound from Example IX in 3 lof methylene chloride is heated to reflux, with stirring. In the courseof 1 h, 95 ml (155 g, 13 mol) of thionyl chloride are added dropwise andthe mixture is stirred for a further 2 h at reflux temperature. Thereaction solution is then cooled to room temperature, concentrated at25-30° C. under reduced pressure until the beginning of crystallizationand admixed with 2.5 l of toluene. At a temperature of 30-40° C., afurther 2.3 l of solvent are distilled off under reduced pressure. Aftercooling to approximately 20° C., 1.2 l of toluene are added to thebatch. The suspension is cooled to 0-5° C., stirred for 1 h at thistemperature, filtered with suction, washed with 1.4 l of toluene andsucked dry. The toluene-moist product is reacted without furthercharacterization.

EXAMPLE XI

458 g of toluene-moist acid chloride, 125 g of R-phenylglycinol and 8.5liters of toluene are introduced into a 20 l flange flask and stirred.Beginning at 20° C., 235 ml (171 g, 1.7 mol) of triethylamine are addeddropwise in the course of 15 min. The mixture is then stirred for 1 hourat 60-65° C., cooled to room temperature and stirred at this temperaturefor 8 h. The precipitated crystals are filtered off with suction, washedwith toluene and sucked dry. After the toluene-moist crystals have beenheated to boiling in 11 liters of ethanol for 15 min, 7.5 liters ofethanol are distilled off and then 8 liters of water at boiling heat areadded. The mixture is stirred for a further 15 min at refluxtemperature. The flask contents are cooled to 20° C. The crystals arefiltered off with suction, washed 3 times, each time with 3.5 liters ofwater, and dried under reduced pressure at 80° C. The dried crudeproduct is recrystallized from approximately 4 liters of methyl ethylketone.

Yield: 383 g (85% of theory) Melting point: 221° C.

EXAMPLE XII

41.9 g (0.2 mol) of 2,4-dimethyl-pyrimido[1,2-a]indole and 33.6 g ofsodium hydrogen carbonate are introduced into 300 ml ofdimethyl-formamide. The mixture is heated to 120° C. and a solution of128.1 g (0.2 mol, 68% strength) of the compound from Example XII(bromide) in 135 ml of dimethylformamide is added dropwise at 30-70° C.in the course of 10 min. The mixture is stirred for 40 min at 120° C.and the reaction mixture is poured into 2.2 l of semi-concentratedsodium chloride solution at room temperature. After extraction with 2.2l of ethyl acetate, the organic phase is washed 3 times withsemi-concentrated sodium chloride solution, dried over sodium sulphateand concentrated at 50° C.

Yield: 165.4 g (70.4% of theory) HPLC: 46.9%

EXAMPLE XIII

165.4 g (0.14 mol) of the crude product from Example XII are dissolvedin 1.6 l of acetone at 50° C. In the course of 10 min, 80 ml (0.48 mol)of semi-concentrated hydrochloric acid are added dropwise at 15 to 20°C. and the mixture is stirred for 2 h at approximately 10° C. Theprecipitated solid is filtered off with suction, washed with a sparingamount of acetone and dried at 50° C. under reduced pressure.

Yield: 60.7 g (39.3% of theory, based on pyrimidoindole) HPLC: 76.1%

EXAMPLE XIV

60.7 g (0.10 mol 76.1% pure) of the compound from Example XII aredissolved in 146 ml of formic acid and 43 ml of 48% strength hydrobromicacid and stirred for 6 h under reflux (109° C.), the reaction mixturefoaming vigorously initially. At room temperature, 94 ml of isopropanoland 187 ml of water are added and, with cooling, in the course of 1 h,the mixture is adjusted to pH 5 by addition of 190 ml of concentratedsodium hydroxide solution. The mixture is stirred for 2 h, the solidsare filtered off with suction and washed three times with isopropanol,each time with 100 ml, and three times with water, each time with 100ml. The residue is stirred for 1 h with 310 ml of isopropanol, filteredoff with suction, washed with a sparing amount of isopropanol and driedunder reduced pressure at 50° C.

Yield: 36.9 g (approximately 100% of theory) HPLC:92.1%

EXAMPLE XV

10 ml (0.14 mol) of thionyl chloride are added dropwise in the course of10 min at 39° C. to a solution of 37.1 g (0.09 mol) of the compound fromExample XIV in 306 ml of dichloromethane, and the resulting gases arepassed into a scrubbing tower. The mixture is stirred under reflux for 2h and volatile portions are distilled off under reduced pressure at 40°C. bath temperature. The remaining thick suspension is admixed with 270ml of toluene, concentrated under reduced pressure at 50° C. and theresidue is stirred with 270 ml of toluene at room temperature for 2 h.The product is filtered off with suction, washed with a sparing amountof toluene and dried under reduced pressure.

Yield: 47 g (toluene-moist)

EXAMPLE XVI

The toluene-moist crude product (47 g, approximately 0.08 mol) fromExample XV is suspended in 810 ml of toluene. 11.8 g (0.086 mol) ofD-phenylglycinol and 23 ml (0.166 mol) of triethylamine are added andthe mixture is stirred at 61 to 63° C. for 1 h. The solids are filteredoff with suction at room temperature and stirred for 2 h with 500 ml ofwater and 50 ml of saturated sodium hydrogen carbonate solution. Thesolids are filtered off with suction, washed with 150 ml of water anddried at 50° C. under reduced pressure.

The crude product (32.3 g) is dissolved in 1 l of methyl ethyl ketone atboiling heat, filtered off hot with suction from insoluble portions, thefiltrate is concentrated to approximately 200 ml and cooled with an icebath. The product which has crystallized out is filtered off withsuction, dried at 50° C. under reduced pressure, dissolved in 2 l ofmethanol at boiling heat, filtered off hot with suction and concentratedto 150 ml. The product which has precipitated out at room temperature isfiltered off with suction, washed with 150 ml of methanol and dried at50° C. under reduced pressure.

Yield: 14.9 g (34.6% of theory) HPLC: 99.9% Melting point: 195-200° C.

What is claimed is:
 1. A compound of the formula (IV)

in which T represents a cycloalkyl having 4 to 12 carbon atoms orrepresents linear or branched alkyl having up to 12 carbon atoms and R⁶represents the D- or L-menthyl radical or tert-butyl, with the exceptionof the compound having T=isopropyl and the compound.


2. A compound of the formula (V)

in which R⁶ represents the D- or L-menthyl radical or represents thetert-butyl radical, T represents a cycloalkyl having 4 to 12 carbonatoms or represents linear or branched alkyl having up to 12 carbonatoms, and R⁷ represents bromine expect for the compound.